This Phase I Small Business Innovation Research (SB1R) application proposes to incorporate dramatic advances in optical coherence tomography (OCT) imaging technology into a microscope-based prototype for use in small animal imaging. This OCT microscope has the potential to become invaluable in rapid phenotyping, in the three-dimensional characterization of microanatomy, and in the quantification of microphysiology. This instrument will be of great interest to scientists who study zebrafish, Xenopus, chick embryo, fruit fly, and other animals of comparable size. These innovations build upon recent work on Fourier-Domain OCT (FD-OCT), an alternative approach to OCT data collection which takes advantage of parallel array detection technology in place of a single sensor as conventionally used. However, the proposed approach extends well beyond the current state of the art in Fourier-Domain OCT by introducing specific design innovations which optimize system sensitivity (defined as the signal-to-noise ratio for an ideal reflective sample, and which can be traded off for acquisition rate) and robustness (defined as system manufacturability and durability), in contrast to current designs which exhibit severe limitations in both areas. The resulting FD-OCT system will be coupled into a standard stereo zoom microscope for simultaneous conventional and tomographic imaging capability.